This invention relates to a cash transaction machine for depositing and withdrawing by the user's manipulation, and more particularly to a cash transaction machine with a function to sterilize or disinfect bills.
A cash transaction machine having a function to sterilize bills is disclosed in JP-A-3-209595, in which sterilization methods by heat, ultraviolet rays, chemicals are revealed. In sterilizing bills by heat sterilization, a method of heating a bill with heating means provided on the transport path is effective. Heat sterilization of bills, such as this, is shown in JP-A-4-114652. In JP-A-4-114652, there is provided a heat sterilizing section, which includes a heating roller containing heating means such as a heater provided on the transport path, and a heat-resistant belt wrapping around the heating roller. Bills are moved between the heating roller and the heat-resistant belt as they are transferred on the transport path, and the bills are heat-sterilized at the bill-holding section including the heating roller and the heat-resistant belt.
In a heat sterilization process in which the heating roller and the heat-resistant belt are raised to a high temperature and while a bill is passed between the heating roller and the heat-resistant belt, the bill is sterilized by heat, the temperature of the bill is at about room temperature at most before it comes in between the heating roller and the heat-resistant belt. In order to raise the bill at this temperature to a sterilizing temperature while the bill is placed between the heating roller and the heat-resistant belt, a large quantity of heat is required. When bills are sterilized successively, the heating roller and the heat-resistant belt are deprived of a considerable quantity of heat in a short time, so that the temperature of the heating roller and the heat-resistant belt fall rapidly. In addition to being deprived of heat by the bills, the heating roller and the heat-resistant belt themselves are radiating heat. Therefore, for heating the heating roller and the heat-resistant belt by the heating means during sterilization, it is necessary to provide a large capacity heat source to supply a quantity of heat equivalent to the deprived quantity of heat. However, it is difficult to install a large capacity heat source for reasons of power consumption, installation space, or the like. An important problem is how to maintain the heating roller and the heat-resistant belt at a sterilizing temperature.
By the examination of the germs on the circulating bills, the present inventors found that various kinds of germs, including staphylococcus aureus and bacillus subtilis adhere to the bills in circulation. Experimental research has been made into the heating condition for thermally killing the microbes including those mentioned above. To give an example, according to "Principal Sterilization and Disinfection in Practice revised edition--" (issued by Nihon Iji Shimposha, Jul. 31, 1989), the sterilizing condition is 5 to 10 min at 60.degree. C. for staphylococcus aureus, and 15 min at 104.degree. C. for bacillus subtilis.
However, in a bill handling machine, when a bill heating section is provided along the transport path and bills are transferred and sterilized one after another, because this kind of machine transfers 7 to 12 bills in one second at the speed of about 1 m per second, even if the heating section is prolonged, the heating time that can be secured per bill is 0.05 to 0.15 s at most, which does not satisfy the heating time as one of the sterilizing conditions mentioned above.
It is known that in the dying process of those germs, if the heating condition is fixed, the number of dead germs increases exponentially. As the heating time is reduced, the germicidal effect is decreased.
Therefore, in a bill handling machine, if a bill heating section is provided on the transport path and the bills which are transferred are sterilized one after another, when the heating time is so short as 0.05 to 0.15 s as mentioned above, by setting a higher heating temperature than in the above-mentioned literature, it is possible to obtain powerful germicidal effects. On the other hand, If the temperature of the heating roller and the belt is raised too high, problems deriving from the machine construction arise such as an increase in heat quantity produced, and danger of smoke generation and catching fire.
Meanwhile, in putting into practical application the sterilizing mechanism in the bill handling machine, it is not necessary to offer such a high germicidal effect as in sterilizing equipment used in medical scenes because a user touches a sterilized bill with his or her contaminated hand in daily life and not a few germs again adhere to the bill while it is stored in the purse. With this taken into consideration, the heating condition should be set.